The objective of this study was to ascertain whether there is an association between amalgam exposure and the mercury levels in urine and whole blood. The age of the 1,127 study participants who had complete clinical and laboratory data was 52.8 years. Overall, 4.8 percent of these participants were edentulous. Dentate individuals averaged 19.9 amalgam surfaces per person, 3.1 ug total mercury per liter in urine (range was 0-35 ug/l), and 2.6 ug total mercury per liter of whole blood (range 0-44 ug/l). Significant correlations were detected between the total number of surfaces with amalgam and total mercury (0.34) and inorganic mercury (0.34) concentrations in urine. In whole blood statistically significant, but biologically weak, correlations were detected between amalgam exposure and total (0.09) and inorganic (0.15) mercury, respectively. The blood 0.15 value was considered trivial and clinically meaningless, as the range of inorganic mercury ranged from non- detectable to a maximum of 6 ug per liter. The moderate correlations for urine are clinically significant in that they are consistent with the suspected inhalation and ingestion of small amounts of mercury from amalgams. This is the first major U.S. study to provide a complete inventory of amalgam exposure in adults, albeit in males only. Other studies have recorded the number of filled surfaces but not the type of material used. This study scored amalgam exposure on all surfaces of all teeth. All subjects were tested for their mercury levels in urine and whole blood. The dose-response between amalgam exposure and urinary mercury levels identified in this study cohort suggests that mercury from their amalgams is being absorbed or ingested. Accurate and valid measurements of amalgam exposure, urine and blood mercury concentrations are important in the assessment of biocompatability of amalgam fillings and populations risk levels.